Drug resistance difference analysis of Escherichia coli in 5 species of white-feathered broilers

【Objective】To conduct epidemiological research and drug resistance difference investigation of Escherichia coli during breeding process of 5 species of white-feathered broilers，and to get information about E.coli drug resistance of different species of white-feathered broilers and difference founded among them，so as to provide reference for guidance of diagnosis and veterinary drug control of broiler diseases.【Method】 Five species of white-feathered broilers（2 imported species with large breeding scale in Jiangsu Province and 3 self-breeding lines in China）were selected as experimental objects，0-day-old meconium samples and 4-，8-，12-，16-，20-，24-，28-，32-，36-and 40-day-old cloacal cotton swab samples were collected.E.coli was isolated by MacConkey medium and identified by PCR.Kirby-Bauer（K-B）method was used for drug sensitivity test.【Result】 978 strains of E.coli isolated from 1075 samples，with a total isolation rate of 91.0%.Guangming No.2（variety A）and Shengze 901（variety C）had the highest isolation rates of E.coli，both of which were 93.0%.WOD168（variety E）had the lowest isolation rate of 88.4%.There was no significant difference in the isolation rate of meconium samples，the isolation rate of 2 replicates，the total separation rate of E.coli and the separation rate of different days of age among the 5 varieties of white-feathered broilers（P>0.05）.The 5 varieties of white-feathered broilers had high resistance to ampicillin（AMP），amoxicillin（AML），erythromycin（E），tetracycline（TE）and chloramphenicol（C），and high sensitivity to amikacin（AK），fosfomycin（FOS），azithromycin（AZM）and ceftriaxone （CRO）.The E.coli strains from 5 species performed obvious multidrug resistance and the drug resistance spectrums of 5 species were different.【Conclusion】 Drug resistance of E.coli in different varieties of white-feathered broilers was affected by environmental factors such as drug habits，feeding methods and conditions，but its multi-drug resistance had certain genetic stability.Therefore，in production，the source of animal breeding should be supervised，intensive breeding should be encouraged and developed，feed safety testing should be strengthened，breeding and epidemic prevention conditions should be improved，the use of drugs should be strictly regulated，the frequency of use of the same drug and bacterial resistance should be reduced to guarantee animal product safety and human health.